We Are Pulling Out

You continue to make your way to your team's extraction point, but once there, things don't go exactly as you might have hoped.

Ride the tram as it begins to climb upward. Vortigaunts will appear outside -- either stay low, or shoot them as they pop up. Once the tram docks, get out and kill the remaining Vortigaunts that appear.

A few steps away, you'll meet a chubby security guard, who currently has his hand stuck in a vending machine. Get him to follow you, and he'll take out most of the enemies that follow.

Upstairs, you'll come to a locked door. Through a window you'll see Barney and Walter chatting, who then get a rude surprise, which upon its conclusion will shatter the glass window. Enter the room via the window, and unlock the door from the other side, allowing Otis in.

Continue along and break the glass if you'd like to talk to the scientist inside the next room. While you're doing that, Otis will unlock a closet with MP5 grenades and ammo.

Hop on the platform at the end of the hall and head upward, where a marine is fighting a losing battle with some Vortigaunts. Finish the aliens and grab the MP5 by the dead Marine's feet.

The door is locked, but there is a vent above the HEV charger. Use the crates to climb up, break the vent's opening, and travel through until you emerge at what appears to be the extraction point.

Once in the base, you can see the extraction helicopter waiting outside -- there's even a Marine waving at you to hurry. Collect as much as you can before proceeding -- you won't be able to retrace your steps shortly.

Upon nearing the outside exit, the hangar door will suddenly close, the G-Man on the other side. The fire door leading back upstairs will also shut, effectively sealing you in while the helicopter takes off, leaving you behind.

A few seconds later, Vortigaunts will break into your area. Eliminate them and escape through the opening one of aliens created when it broke in...